As is known, in scanning SQUID microscopy a Superconducting Quantum Interference Device (SQUID), which is incorporated into a Scanning SQUID Microscope, is used to obtain a magnetic field image of a sample. By scanning very close to the surface of the sample, good spatial resolution can be obtained in the resulting image. Recent research on room-temperature SQUID microscopy (the sample is at room temperature) has focused on improving the spatial resolution achieved under typical operating conditions either through hardware or software improvements. For example, using a magnetic inverse transformation, it is possible to transform a magnetic image into an image of the source currents. The spatial resolution of the resulting current density image can be up to ten times (10×) better than the raw magnetic field image or up to 5 times smaller than the SQUID-sample separation z under typical conditions, limited by the strength of the magnetic signal and the noise in the SQUID. This result is only possible because the data from a SQUID is quantitatively very precise and accurate, allowing a complicated transformation to be reliably performed without introducing significant distortion.
One drawback of the scanning SQUID microscope is that scanning very close to the surface of the sample to obtain good spatial resolution, as described above, also undesirably introduces position noise into the magnetic field data and results in distortion or other degradation of the subsequently formed images thereof. It has been further determined that even quite small amounts of position noise introduced to the magnetic field data during scanning can significantly degrade the subsequently formed images.
It would, therefore, be desirable to overcome the aforesaid and other disadvantages.